CR engine HPFP analysis

[Nimbus]

Quote:This makes sense to me and would explain why failure is sudden and catastrophic. The followup question would be how and why could a fuel starvation/lubrication condition occur at the cam roller interface?

Ok.... at the top of my list for root cause possibilities is the following:

Based on the design, its seems that VW took great pains to supply fuel to the cam/roller chamber and the HPFP (3 pumps in the fuel system - amazing). In fact, there are enough sensors to put the engine in "emergency mode" (page 37) giving me the impression that VW will not allow the engine to be run hard without the fuel system running as intended. So, instead of fuel starvation I'm thinking that the fuel used in the failed pumps does not have enough lubricity. I've stated this in other posts (see below - post #105), but the more I look into this issue the more a fuel additive seems required to minimized the potential for HPFP failure. We should not have to use an additive, but unless you can verify that the majority of fuel you use has a lubricity with an HFRR value of <460 microns you should use an additive. US fuel specification is <520 microns. See the following thread for more info on HFRR values.
http://forums.tdiclub.com/showthread.php?t=282077&page=7

 

[Timujin]

Great info!

 

[VWSHPFRMN]

Failure Facts

Ok guys, here's the facts on the failure of the pump in the labeled photos in the first post. This car was in my shop. The customer broke down a few blocks from the gas station after filling up. Upon initial inspection we opened the fuel filter canister and found no metal. The fuel was cloudy and white in color. It smelled like turpentine but not gasoline. The fuel felt oily to the touch. We drained the tank, cleaned out the lines, added fresh diesel and primed the system. The vehicle seemed to run ok so we released the vehicle to the customer but warned him of possible future problems. We also gave him a sample of the fuel. I was worried about the low pressure fault it had when it came in. The next day the car returned on a hook just as I feared. The fuel canister had metal in it this time. The fuel sample we gave the customer was still cloudy but had developed water droplets on the bottom of the jar. I can tell everyone for sure that this pump failed from contaminated fuel. Lesson learned, next car I find with no metal but suspect fuel, I will pull the piston out of the pump and inspect the roller for damage.

The thread started by KNOWLEDGE where his fuel canister was rusted and we found rust in his tank did not need a complete fuel system. On his car we found the rust by pure luck. We were chasing down a drivability concern which ended up being the 5 volt signal wire on the charge pressure sensor rubbing on the a/c pipe on the compressor. It was dumb luck that we opened the canister and found rust.We found no contaminated fuel. We cleaned the tank, replaced the lift pump and fuel canister . The car has been running fine to this day.

 

[sgoldste01]

Ok.... at the top of my list for root cause possibilities is the following:

Based on the design, its seems that VW took great pains to supply fuel to the cam/roller chamber and the HPFP (3 pumps in the fuel system - amazing). In fact, there are enough sensors to put the engine in "emergency mode" (page 37) giving me the impression that VW will not allow the engine to be run hard without the fuel system running as intended. So, instead of fuel starvation I'm thinking that the fuel used in the failed pumps does not have enough lubricity. I've stated this in other posts (see below - post #105), but the more I look into this issue the more a fuel additive seems required to minimized the potential for HPFP failure. We should not have to use an additive, but unless you can verify that the majority of fuel you use has a lubricity with an HFRR value of <460 microns you should use an additive. US fuel specification is <520 microns. See the following thread for more info on HFRR values.
http://forums.tdiclub.com/showthread.php?t=282077&page=7

And which additives do you recommend? It seems to me that CR TDI owners don't want an additive that will separate water from the fuel. If that's true, which additives are safe for CR TDIs while adding the necessary lubricity? We don't want to solve one problem and create another by using the wrong additives.

Doesn't Stanadyne Performance Formula separate water from the fuel? Doesn't Stanadyne sell a lubricity-only product that doesn't boost cetane or separate water? Wouldn't that be a good choice?

 

[Plus 3 Golfer]

And which additives do you recommend? It seems to me that CR TDI owners don't want an additive that will separate water from the fuel. If that's true, which additives are safe for CR TDIs while adding the necessary lubricity? We don't want to solve one problem and create another by using the wrong additives.

How many times does this have to be answered B2

 

[ddschwaner]

imo 50% plus failures are due to negligence of putting gasoline or bad diesel fuel in the tank

 

[Nimbus]

And which additives do you recommend? It seems to me that CR TDI owners don't want an additive that will separate water from the fuel. If that's true, which additives are safe for CR TDIs while adding the necessary lubricity? We don't want to solve one problem and create another by using the wrong additives.

Good question. I think everyone should do their own research on this one because, as you stated, its not clear which way to go on this. If the CR systems still had a water separator in the fuel filter it would make the decision easier. (clarification - CR fuel filters will separate water, but there is no easy method of draining the water, except during filter changes. Using an additive that helps to separate the water from the fuel is a good thing for the fuel system as long as filter maintenance is performed at the correct interval and the fuel is not contaminated with large amounts of water).

For me, I use the Stanadyne Lubricity formula because I know (and work with) engineers that have worked for Stanadyne and VW has approved this particular formula ("approved" may be a strong word here but its clear that if they had to pick one, this would be it).

 

[Mike_M]

imo 50% plus failures are due to negligence of putting gasoline or bad diesel fuel in the tank

I'm not criticizing or contradicting this, but on what experience do you base it?

 

[sgoldste01]

How many times does this have to be answered B2

I don't have access to biodiesel in Rochester, NY.

 

[oilhammer]

Thanks Pete for your contributions, and thanks to everyone for sharing information.

I got another failed pump sent to me today.... same exact thing, galded up piston roller, worn shaft cam lobes. This one had no sign of rust either, and the little dribbles of fuel left in the pump seemed 'normal' to me. This car had 37k miles.

 

[Norm0770]

I'm glad that someone outside of VW is able to get these pumps, analyze them and share the information, but why are VW and/or Bosch not keeping them to do their own analysis and find a solution? The information is good to have and I seems to be pointing toward low lubricity of the ULSD, so when our Golf arrives I'll be adding Stanadyne lubricity formula at every fill-up.

On the other hand all of the information we get here won't solve the problem, VW and Bosch have to do that, but it may allow owners to do things to prevent or postpone HPFP failure.

 

[numl0ck]

I've read some questions on this thread that can be anwsered by the following pdf. Not sure how long this will remain on the web, so save a copy.

http://www.dsd.go.th/itrain/km/kboc/2552_Test_Project_WSC40/Automobile/DOC33_IL_40CA/DOC33_IL_40CA_1680_Diesel_Engine_2.0L_TDI_CommonRail_BIN5_UL.pdf

I'm guessing it's down because I can't get to it anymore.

 

[manual_tranny]

I saved a copy PM me to get an e-mail. Less than 5MB. Also if you give Google a chance it will find a cached version for you (albeit without pictures)

 

[740GLE]

Oil hammer, can you inspect the pump for the fine mesh filters that are internal to the pump by the metering valve and overflow valve? See if these collected enough crap to cause the to clog up.

 

[oilhammer]

This little mesh screen is clean on both the pumps I have here. One seems to have a couple tiny 'flecks' of gray stuck in it, but nothing what you would think to see given the amount of wear on the internals. That screen must not filter anything after the pump itself.

 

[740GLE]

I’m no fluid dynamic expert, but looking at the exploded view of the pump, what’s stopping the fuel from going directly from the inlet up to the high pressure metering valve, bypassing flowing in and around the cam and pistons. It’d be interesting to see the long term flow patterns of fresh fuel in and around the cam and roller. Maybe this would lead to a certain operating condition being detrimental to the HPFP, long term idling, low fuel consumption results in the fuel braking down surrounding the roller and causing wear. It’d be interesting to mount a temperature probe in the HPFP and see how different conditions affect fuel temp and thus the lubricity.

Maybe the turbulence of the cam rotating messes with the flow enough so that fresh fuel is mixed and flushed through while underway, not sure.
​

Wouldn’t there be better protection of friction component, cam, roller, piston, if fresh fuel enters in one side flowed across all components then out the opposite end to the high pressure metering valve and then rail? Would changing this lay out prevent HPFP failures? Who knows? But if the name of the game is keeping things lubricated as much as possible I can’t see this would be worse off, only down side is routing of fuel lines would be messy.

 

[milesstandish]

looks like the fuel inlet goes directly to the fuel metering valve, then to the inlet valve to the compression chamber, and then to the exhaust/check valve.

the fuel around the cams/piston act as a kind of reservoir for fuel inlet to the metering valve.

the entire system is at one pressure during piston downstroke, and then during piston upstroke the compression chamber sees much higher pressure than the inlet, and the compressed fuel forces open the exhaust/check valve.

when it functions, looks like flow only goes one direction via pressure differential.

 

[740GLE]

This little mesh screen is clean on both the pumps I have here. One seems to have a couple tiny 'flecks' of gray stuck in it, but nothing what you would think to see given the amount of wear on the internals. That screen must not filter anything after the pump itself.

I guess that would go hand in hand with the actual flow of fuel through the pump. Thinking out loud, if the inlet and return line are orientated so that fresh fuel enters the top, flows through the cam roller then exits through a mesh screen at the bottom to the metering valve/return line. Wouldn’t this force particles through the mesh filter, or at least away from cam and roller interferences? Who knows the filtering capability of those screens, but I imagine they are there for a reason.


Not 100% about the orientation of supply return with respect to gravity vs how it looks like in the PDF. The way it looks now it almost seems that partials/shaving will settle in a bowl and collect at each shutdown building up quantity over time.

​

I’m also curious how the HPFP deals with a hard shut down, IE stalling the car with those people who’ve had to relearn to drive a stick. I’ve had some hard stalls and I can’t imagine how this has affected everything.

 

[Elfnmagik]

Have you guys read this?

http://forums.tdiclub.com/showpost.php?p=3011758&postcount=54

 

[milesstandish]

fuel from the fuel filter enters the pump near the bottom, not the top

the top of the pump is where the fuel is compressed and sent to the rail

 

[milesstandish]

The PDF drawing of the hpfp is not orientated as the pump is mounted on the engine. Pull your enine cover and look at the hpfp. Both the supply and return fuel lines are towards the TOP of the hpfp.

Also fuel from the fuel filter goes to the boost pump first,then pumped by the boost pump to the hpfp.
Dweisel

o great, i hadn't pulled off the cover, thanks

so the pdf is more or less upside down. that answers my question about how fuel is able to lube the spring "above" the roller.

 

[dubStrom]

Have you guys read this?

http://forums.tdiclub.com/showpost.php?p=3011758&postcount=54

Complex engine. I'd sure like to get my hands on a Eurospec or Australian version (sans extreme CARB spec particulate filtration).

 

[tdidieselbobny]

How many times does this have to be answered B2

Ummm, that is if you can FIND it here in WNY.....the one place that does make bio out of used oil in Buffalo doesn't sell it retail. There are no outlets for biodiesel here in WNY- ethanol is a different story.

 

[Slo.Mo.Shun]

Can someone send documentation to VWoA.

They told me any documentation of failures can be mailed to:

VWoA.

3499 w Hansen rd Rochester Michigan 48309.

 

[oilhammer]

Can the mods PLEASE delete all this FSI nonsense from this thread?

 

[bsalbrig]

Is the lifter roller on needle bearings?

 

[oilhammer]

Is the lifter roller on needle bearings?

No, just a roller kind of pinch in the piston on a pin.

 

[Slo.Mo.Shun]

Can the mods PLEASE delete all this FSI nonsense from this thread?

I just did.

 

[bsalbrig]

No, just a roller kind of pinch in the piston on a pin.

Have you had one apart to see if the pin/roller is wearing on the inside?

 

[KraftwerkB6]

I could not find the other thread with the HPFP talking that i was doing in it. But anyways this is fine.

In light of something i have just seen i would heavily suggest if your not already. saving your fuel recipts from the gas stations and maybe might go as far as to staring bringing leftover water bottles and filling them up half with the same fuel as your filling your car with. So u can see for yourself if the fuel is OK or not./ If it seperates and there is water i would talk to the manager of the filling station or stop going there ASAP.

Also i would ask if the filling station is using fuel that complys with ASTM-D-975 Grade 2 S15 B5 or less biodiesel content standards. And better off if they are, then to keep filling in that same station.

I have filled my vehilce with the same Shell station next to my house except for original tank from dealer and 2 stations in WV. and that was my first 3 tanks. Other then that it has been the same station.

From what i have just read it sounds like VW is not going to cover **** if the filling station is to blame for water in tank,rust in tank, or anything besides fuel in thier holding tanks and what gets in your fuel system might not be thier fault. More of a contaminated or incorrect fuel can cause the problem not a faulty HPFP.

Just something to think about.